Hello and welcome to our web page here my name is***** a Certified Volvo Car Expert Mechanic.I'm going to try today to answer your question.
what fault codes do you have what part did your mechanic told you to replace ?
I have no fault codes.
The mechanic said it could be anything from a sensor fault right up to replacing the whole control unit. He did mention a software upgrade as a starting point.
He said these were normally provide FOC by a volvo dealer during service.
This problem was resolved by sending the car to my local Volvo dealership.
Sorry you could not help
Thank you< the matter is now fully resolved.